Concomitant drug use and polydrug abuse are often overlooked in treatment programs for compulsive drug users. Studies of drug and alcohol cessation programs have demonstrated that the use of licit drugs with which patients have access, such as caffeine or nicotine, increases during the period of treatment. Therefore, investigating the potential behavioral and pharmacological mechanisms of how drug cues modulate associations with other rewarding stimuli will help us understand the potential impact of licit drug use during and after treatment for compulsive drug use. The experiments in this proposal utilize a Pavlovian conditioning procedure in which one cue modulates conditioned responding to a second cue. Specifically, in the presence of the stimulus effects of nicotine or amphetamine, the environmental cue will always be followed by sucrose; in the presence of saline, the cue will never be followed by sucrose. Thus, the drug state sets the occasion upon which food is available after the exteroceptive cue. The experiments will examine the specificity with which the drug stimuli modulate conditioned responding and some possible associative mechanisms. For example, are the drug cues sensitive to changes in their stimulus effects? Could these modulators serve as "global" cues or are they specific to discriminative situations in which they were trained? What are the potential associative mechanisms of the modulators? Based on preliminary findings as well as research and theory, we predict that changing the physical properties of the modulators will change their stimulus effects within the organism and reduce their behavioral efficacy. In addition, the modulators will probably have little direct "associative" strength and could potentially be used to solve discriminations in which they were never trained.